1. Field of the Invention
The present invention relates to a driver that drives an external device such as a motor.
2. Related Art
In a conventional technology that improves a power factor of the external device such as the motor, PFC (Power Factor Corrector) has been used. Ordinary PFC has adjusted a waveform of a current (hereinafter referred to as “charge current”) so as to have a waveform similar to a waveform of a driving voltage for the external device in order to improve the power factor.
However, conventional PFC (see JP-A 2006-510340 (Kokai), JP-A 2001-37254 (Kokai), JP-A H10-201248 (Kokai), and “Correcting Power Factor-Saving Cost using Digital Control- (pages 44-48, EE Times Japan April issue in 2009, on Apr. 17, 2009)”) has required a signal pass to sense the driving voltage or a driving current. Therefore, the number of elements included in the PFC has been increased. That is, a special sensor for the PFC has been required. As a result, a circuit area and a consumed power of the PFC have been increased. Therefore, a cost of manufacturing the PFC has been increased.